Building control systems perform automated operations within a building or series of buildings. Building control systems include comfort (i.e. HVAC) systems, security systems, lighting systems, and fire safety systems. In addition to other functions, one function of building control systems is to alert users in the case of an event occurrence that warrants attention.
Building control systems typically generate event notifications if one or more elements or conditions within or monitored by the system are operating out of boundaries. Event notifications may be generated for many reasons, including notification of a potentially dangerous or destructive condition, or of a type of malfunction affecting productivity. For example, a building heating, ventilation and air conditioning (“HVAC”) system may exhibit various event notifications that indicate anything from a serious health threat, such as an air conditioning “chiller” plant failure, to a minor error status report, such as the failure of a single temperature sensor. Building fire systems also, for obvious reasons, generate various event notifications ranging from the existence of a fire and/or smoke condition to the need for routine maintenance for one or more smoke detectors.
Large building systems increasing employ data networks to transmit information, including event information, to one or more “control” locations in which event status and other system status information may be monitored. The Apogee brand building automation system, available from Siemens Building Technologies, Inc. of Buffalo Grove, Ill., is an example of a building control system that employs data networks to communicate alarm information as well as other information to one or more operator stations.
A continuing issue with large building systems arises from the presentation of system information, and particularly event (e.g. alarms), to system operators. Building systems often employ hundreds or thousands of devices that generate data. For example, a fire safety system for a campus of buildings may include scores of smoke detectors, emergency pull stations (the red, pull handles that trigger an alarm), heat detectors and other devices that generate data, event notifications and/or alarms of different priority or importance. It is critical that an operator be able to obtain event notifications and identify their source location within the building or site in an expeditious manner.
In the past, event information was presented to one or more control computers and then displayed on the computer display in a primarily text-based format. The textual information would typically identify of the device or panel that generated the event. The textual information might also identify the severity of an event, such as an alarm. The problem with a text-based event/alarm notification system is the difficulty in navigating through event information in a meaningful way. In particular, text information is typically provided as a list, which provides little or no intuitive information on location, distribution or grouping of events.
To address such drawbacks, graphical user interfaces have been employed in fire safety systems, as well as other systems. Graphical user interfaces allow users to navigate through event notification information in an intuitive and convenient way. One such graphical user interface is a system that allows the user to view hierarchical system maps that show various levels of detail (i.e. zoom levels). For example, one screen may show a map of an entire campus of several buildings. Another zoom level screen may show one of the buildings of the campus in further detail, illustrating the different floors of the building. Still another screen may show one of the floors of the building, illustrating a floor plan of the different rooms or zones of the floor. Such a system allows the user to selectively monitor the entire site or select portions of the site. An example of a system with these graphical capabilities is the FireWorks fire system workstation available from Edwards System Technologies, Inc, part of GE Security.
Manipulation of event/alarm data in a hierarchical system to enable such graphics, as well as other notification applications, can be accomplished in a number of ways. U.S. patent application Ser. No. 10/434,491, filed May 8, 2003 teaches a system of hierarchical graphic elements in which alarm indications for downstream elements in the hierarchy are automatically displayed with a particular graphic element. That system involves managing, for each graphic element, a list of all downstream elements that may have an alarm condition that should be displayed in the graphic element. During operation, when a graphic element is displayed, it includes alarm conditions of any of the downstream elements on its list.
To illustrate further this system, consider an example of a graphic element of a system is representative of a building floor. The graphic element of the floor would include alarm links for each room of the floor as well as for each sensor in each room on the floor. Thus, if one of the controllers in the room goes into alarm, then when the graphic element for the building floor is displayed, it will determine that one of its alarm links is in alarm and display the presence of that alarm.
A potential limitation to such a system is that in large systems, certain nodes will have hundreds or even thousands of descendant nodes for which alarm information should be available. For example, in a graphic view of a node representative of a floor of a large building, it may be desired to display any alarms from any of the devices in any of the rooms of the floor. Thus, the “floor” node would have alarm links to all of those devices. When the display is generated, the alarm information for all of the devices must be obtained and processed. In larger systems, such a display operation can be computationally intense, and may require significant use of communication channels in some cases.
There is a need, therefore, for a method and apparatus of manipulating alarm, or more generally, event data, in a system wherein graphics, text displays, or other application can access event information for related nodes throughout a hierarchical node structure with reduced computational effort.